You need IOS which support Autonomus AP mode:

k9w7 - autonomous (or "site survey") IOS
k9w8 - full lightweight IOS
rcvk9w8 - lightweight recovery image

So any image with k9w7, for example c1240-k9w8-mx.124-25e.JAP4. If it’s k9w8, you need controller for the configuration.

Step 1: Delete existing lightweight IOS

delete /recursive /force flash:c1240-k9w8-mx.124-25e.JAP4

Step 2: Power off the AP, press mode button for a while. The AP will fallback recovery mode with IP address in range.

Step 3: Connect the AP LAN with you laptop/PC and set IP Run tftp server.

Step 4: Type the following command to initialize the and upload new IOS.

ap: tftp_init
ap: ether_init
ap: flash_init

ap: tar -xtract tftp:// flash:

ap: set


ap: reset

I am using WPA for security, bellow link for full configuration:


I found following video very help, specially if want to know more about the recovery process.